The electrolytic coupling of nitriles to produce dinitriles is known. See for example Sloan U.S. Pat. Nos. 3,488,267, and also 3,193,480 to Baizer.
The chemical formation of unsaturated dinitriles using precious metal catalysts is disclosed in U.S. Pat. Nos. 4,211,725 and 4,211,725 to Kluger et al.